U.S. patent application number 14/202575 was filed with the patent office on 2014-09-11 for piezoelectric vibrating piece, piezoelectric vibrator, oscillator, electronic apparatus and radio controlled timepiece.
This patent application is currently assigned to SII Crystal Technology Inc.. The applicant listed for this patent is SII Crystal Technology Inc.. Invention is credited to Masanori TAMURA.
Application Number | 20140254329 14/202575 |
Document ID | / |
Family ID | 51487655 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140254329 |
Kind Code |
A1 |
TAMURA; Masanori |
September 11, 2014 |
PIEZOELECTRIC VIBRATING PIECE, PIEZOELECTRIC VIBRATOR, OSCILLATOR,
ELECTRONIC APPARATUS AND RADIO CONTROLLED TIMEPIECE
Abstract
A piezoelectric vibrating piece is provided including: a pair of
vibrating arm sections; a base section which is provided between
the pair of vibrating arm sections; and connecting sections which
connect base end sections of the pair of vibrating arm sections and
a base end section of the base section, in which the vibrating arm
sections have bending points and the vibrating arm sections extend
in a direction away from the base section from the base end
sections of the vibrating arm sections to the bending points, and
the vibrating arm sections extend along the base section from the
bending points to leading end sections of the vibrating arm
sections.
Inventors: |
TAMURA; Masanori;
(Chiba-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SII Crystal Technology Inc. |
Chiba-shi |
|
JP |
|
|
Assignee: |
SII Crystal Technology Inc.
Chiba-shi
JP
|
Family ID: |
51487655 |
Appl. No.: |
14/202575 |
Filed: |
March 10, 2014 |
Current U.S.
Class: |
368/47 ; 310/344;
310/370; 331/116R |
Current CPC
Class: |
H03B 5/32 20130101; H03H
9/21 20130101; G04R 20/10 20130101 |
Class at
Publication: |
368/47 ;
331/116.R; 310/370; 310/344 |
International
Class: |
H01L 41/08 20060101
H01L041/08; H03B 5/32 20060101 H03B005/32; H01L 41/053 20060101
H01L041/053; G04R 20/14 20060101 G04R020/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2013 |
JP |
2013-048454 |
Claims
1. A piezoelectric vibrating piece comprising: a pair of vibrating
arm sections; a base section which is provided between the pair of
vibrating arm sections; and connecting sections which connect base
end sections of the pair of vibrating arm sections and a base end
section of the base section, wherein the vibrating arm sections
have bending points and the vibrating arm sections extend in a
direction away from the base section from the base end sections of
the vibrating arm sections to the bending points, and the vibrating
arm sections extend along the base section from the bending points
to leading end sections of the vibrating arm sections.
2. The piezoelectric vibrating piece according to claim 1, wherein
in an extending direction of the base section, when a length from
the base end sections to the leading end sections of the vibrating
arm sections is L1, and a length from the base end sections of the
vibrating arm sections to the bending points is L2, L2/L1>0.17
is satisfied.
3. The piezoelectric vibrating piece according to claim 1, wherein
widened sections of which width dimensions are wider than that of
the base end sections of the vibrating arm sections are formed in
leading end sections of the vibrating arm sections.
4. The piezoelectric vibrating piece according to claim 1, wherein
the base section extends to the vicinity of the leading end
sections of the vibrating arm sections.
5. The piezoelectric vibrating piece according to claim 1, wherein
groove sections extending along a longitudinal direction of the
vibrating arm sections are formed in main surfaces of the vibrating
arm sections.
6. A piezoelectric vibrator comprising: the piezoelectric vibrating
piece according to claim 1 in a package which is hermetically
sealed, wherein the piezoelectric vibrating piece is mounted in the
package in the base section.
7. An oscillator comprising: the piezoelectric vibrator according
to claim 6, wherein the piezoelectric vibrator is electrically
connected to an integrated circuit as an oscillator.
8. An electronic apparatus comprising: the piezoelectric vibrator
according to claim 6, wherein the piezoelectric vibrator is
electrically connected to a timer section.
9. A radio controlled timepiece comprising: the piezoelectric
vibrator according to claim 6, wherein the piezoelectric vibrator
is electrically connected to a filter section.
Description
RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.119
to Japanese Patent Application No. 2013-048454 filed on Mar. 11,
2013, the entire content of which is hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a piezoelectric vibrating
piece, a piezoelectric vibrator, an oscillator, an electronic
apparatus and a radio controlled timepiece.
[0004] 2. Background Art
[0005] In the related art, a piezoelectronic resonator is known
which includes a piezoelectric vibrating piece having a pair of
vibrating arm sections and a base section, and accommodates the
piezoelectric vibrating piece in a package by fixing the base
section provided between the pair of vibrating arm sections in the
package (see, JP-A-2006-345517 and JP-A-2006-345519).
SUMMARY OF THE INVENTION
[0006] However, according to the related art described above, with
a size reduction of the piezoelectronic resonator, when vibrating
or when receiving impact from outside, it is possible for corner
sections of the leading end sections and outer side surfaces of the
pair of vibrating arm sections to come into contact with a leading
end section of the base section, resulting in cracks, defects or
the like in the leading end sections of the vibrating arm sections.
If cracks, defects or the like occur in the leading end sections of
the vibrating arm sections, impact resistance and reliability of
the piezoelectric vibrating piece decrease.
[0007] Accordingly, a configuration in which contact with the
leading end sections of the vibrating arm sections and the base
section is avoided by increasing a length of a connecting section
that connects the base section and the base end section of the
vibrating arm sections is conceivable, in other words, by widening
a distance of a fork section between the vibrating arm sections and
the base section, and by widely maintaining a clearance between the
leading end section of the base section and the leading end
sections of the vibrating arm sections. However, it is known that
if the length of the connecting section is increased, since the
connecting section itself is liable to vibrate, an equivalent
serial resistance value R2 (hereinafter, referred to as R2) in a
secondary vibration mode decreases. Therefore, the piezoelectric
vibrating piece conducts bending vibration not in a desired
fundamental wave mode but in the secondary vibration mode or in a
high-order vibration mode. That is, if the length of the connecting
section is increased, there is a problem that a desired frequency
cannot be obtained.
[0008] Thus, the invention is made in view of the above situations
and an object of the invention is to provide a piezoelectric
vibrating piece capable of avoiding contact with leading end
sections of vibrating arm sections and a base section while being
vibrated in a fundamental wave mode in the piezoelectric vibrating
piece in which the base section is provided between a pair of
vibrating arm sections. Further, another object of the invention is
to provide a piezoelectric vibrator, an oscillator, an electronic
apparatus and a radio controlled timepiece having such a
piezoelectric vibrating piece.
[0009] According to an aspect of the invention, there is provided a
piezoelectric vibrating piece including: a pair of vibrating arm
sections; a base section which is provided between the pair of
vibrating arm sections; and connecting sections which connect base
end sections of the pair of vibrating arm sections and a base end
section of the base section, in which the vibrating arm sections
have bending points and the vibrating arm sections extend in a
direction away from the base section from the base end sections of
the vibrating sections to the bending points, and the vibrating arm
sections extend along the base section from the bending points to
leading end sections of the vibrating arm sections. Moreover, the
bending point referred to as herein does not necessarily mean only
"bending" and may mean "curving" that is gently curved in the
vibrating aim.
[0010] In the piezoelectric vibrating piece, in an extending
direction of the base section, when a length from the base end
sections to the leading end sections of the vibrating arm sections
is L1, and a length from the base end sections of the vibrating arm
sections to the bending points is L2, L2/L1>0.17 may be
satisfied.
[0011] In the piezoelectric vibrating piece, widened sections of
width dimensions that are wider than that of the base end sections
of the vibrating arm sections may be formed in leading end sections
of the vibrating arm sections.
[0012] In the piezoelectric vibrating piece, the base section may
extend to the vicinity of the leading end sections of the vibrating
arm sections.
[0013] In the piezoelectric vibrating piece, groove sections
extending along a longitudinal direction of the vibrating arm
sections may be formed in main surfaces of the vibrating arm
sections.
[0014] In addition, according to another aspect of the invention,
there is provided a piezoelectric vibrator including: the
piezoelectric vibrating piece according to the aspect of the
invention in a package which is hermetically sealed, in which the
piezoelectric vibrating piece is mounted in the package in the base
section.
[0015] In addition, according to still another aspect of the
invention, there is provided an oscillator including: the
piezoelectric vibrator according to the aspect of the invention, in
which the piezoelectric vibrator is electrically connected to an
integrated circuit as an oscillator.
[0016] In addition, according to still another aspect of the
invention, there is provided an electronic apparatus including: the
piezoelectric vibrator according to the aspect of the invention, in
which the piezoelectric vibrator is electrically connected to a
timer section.
[0017] In addition, according to still another aspect of the
invention, there is provided a radio controlled timepiece
including: the piezoelectric vibrator according to the aspect of
the invention, in which the piezoelectric vibrator is electrically
connected to a filter section.
[0018] According to the piezoelectric vibrating piece of the aspect
of the invention, in the piezoelectric vibrating piece in which the
base section is provided between the pair of vibrating arm
sections, it is possible to provide the piezoelectric vibrating
piece capable of avoiding contact with the leading end sections of
the vibrating arm sections and the base section while conducting
the vibration in the fundamental wave mode. Further, it is possible
to provide the piezoelectric vibrator, the oscillator, the
electronic apparatus and the radio controlled timepiece having such
a piezoelectric vibrating piece.
[0019] Specifically, since the distance between the leading end
sections of the vibrating arm sections and the base section can be
widened without widening the clearance of the fork section formed
between the vibrating arm sections and the base section, it is
possible to avoid contact with the leading end sections of the
vibrating arm sections and the base section while realizing the
bending vibration in the fundamental wave mode without decreasing
R2.
[0020] Further, when the length from the base end sections to the
leading end sections of the vibrating arm sections is L1, and the
length from the base end sections of the vibrating arm sections to
the bending points is L2, if L2/L1>0.17 is satisfied, it is easy
to further reliably conduct the bending vibration in the
fundamental wave mode.
[0021] Further, according to the piezoelectric vibrator, the
oscillator, the electronic apparatus and the radio controlled
timepiece of the aspect of the invention, it is possible to improve
the operation reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is an external perspective view of a piezoelectric
vibrator according to an embodiment of the invention.
[0023] FIG. 2 is an internal configuration view of the
piezoelectric vibrator illustrated in FIG. 1.
[0024] FIG. 3 is a cross-sectional view of the piezoelectric
vibrator taken along line A-A illustrated in FIG. 2.
[0025] FIG. 4 is a plan view of a piezoelectric vibrating
piece.
[0026] FIG. 5 is a view illustrating a cross-section in line B-B of
FIG. 4.
[0027] FIG. 6 is a configuration view illustrating an oscillator
according to an embodiment of the invention.
[0028] FIG. 7 is a configuration view illustrating an electronic
apparatus according to an embodiment of the invention.
[0029] FIG. 8 is a configuration view illustrating a radio
controlled timepiece according to an embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Hereinafter, a piezoelectric vibrating piece, a
piezoelectric vibrator, an oscillator, an electronic apparatus and
a radio controlled timepiece according to an embodiment of the
invention will be described.
[0031] For example, as illustrated in FIGS. 1 to 3, a piezoelectric
vibrator 1 of the embodiment is a surface mount type piezoelectric
vibrator 1 which includes a box-shaped package 5 formed of a base
substrate 2 and a lid substrate 3 which are bonded through a
bonding material 35, and a piezoelectric vibrating piece 4
accommodated in a cavity C which is sealed inside the package 5.
Moreover, the form of the package 5 is not limited to the
embodiment and may be a ceramic package having a base substrate of
ceramic, a frame member, and a lid substrate made of metal.
[0032] External electrodes 38 and 39 disposed in the base substrate
2 are electrically connected to the piezoelectric vibrating piece 4
by a pair of penetration electrodes 32 and 33 passing through the
base substrate 2. In case of the ceramic package, electrical
connection between the inside and the outside of the package can be
achieved by forming the penetration electrodes in the base
substrate of the ceramic or by leading out the electrodes from
between multi-layered ceramic substrates.
[0033] For example, as illustrated in FIG. 4, the piezoelectric
vibrating piece 4 includes a tuning fork type piezoelectric plate
24 formed from a piezoelectric material such as crystal, lithium
tantalate or lithium niobate, and conducts bending vibration by
applying a predetermined voltage. Moreover, when roughly dividing
the bending vibration, there is a fundamental wave mode and a
high-harmonic wave mode, and in order to obtain a desired frequency
(for example, 32.768 kHz), it is necessary to vibrate in the
fundamental wave mode. In order to vibrate in the fundamental wave
mode, it is necessary that R1<R2 if an equivalent serial
resistance value R1 (hereinafter, referred to as R1) of the
fundamental wave mode of the piezoelectric vibrating piece 4 and an
equivalent serial resistance value R2 of a secondary high-harmonic
wave mode are compared to each other. That is, since the
piezoelectric vibrating piece 4 conducts the bending vibration in
the lowest mode of the equivalent serial resistance value, in order
to conduct the bending vibration in the fundamental wave mode, it
is necessary to decrease R1 and increase R2. On the other hand, if
R2 decreases and R1>R2, the piezoelectric vibrating piece 4
vibrates in the secondary high-harmonic wave mode.
[0034] The piezoelectric plate 24 includes a pair of vibrating arm
sections 10 and 11 disposed across a central axis O; a base section
12 that is disposed between the pair of vibrating arm sections 10
and 11, and is fixed to the outside; and a pair of connecting
sections 13 and 14 that connect base end sections 10a and 11a of
the pair of vibrating arm sections 10 and 11, and a base end
section 12a of the base section 12. Moreover, a dimension of the
vibrating arm sections 10 and 11 in a length direction is set to be
a distance two times or more (a distance between the vibrating arm
sections 10 and 11 in the base end sections 10a and 11a) between
the vibrating arm sections 10 and 11. Further, the base section 12
extends to the vicinity of leading end sections of the vibrating
arm sections 10 and 11. Here, the vicinity of the leading end
sections refers to a side of the leading end from a midpoint of the
vibrating arm sections 10 and 11 in a longitudinal direction.
[0035] Widened sections are formed in leading end sections 10b and
11b of the pair of vibrating arm sections 10 and 11. That is, the
pair of vibrating arm sections 10 and 11 are hammerhead types in
which a width dimension of the leading end sections 10b and 11b is
widened compared to that of the base end sections 10a and 11a, and
a weight of the leading end sections 10b and 11b of the vibrating
arm sections 10 and 11, and a moment of inertia when vibrating are
higher. Therefore, the vibrating arm sections 10 and 11 easily
vibrate and it is possible to shorten lengths of the vibrating arm
sections 10 and 11, and to achieve a size reduction. Moreover,
here, the vibrating arm sections 10 and 11 of the hammerhead type
are described but the piezoelectric vibrating piece to which the
invention is applicable is not limited to the hammerhead type. That
is, the piezoelectric vibrating piece may be a type in which the
width dimension of the leading end sections 10b and 11b is
substantially the same as that of the base end sections 10a and
11a, and the piezoelectric vibrating piece may be a type in which
the leading end sections 10b and 11b are tapered as compared to the
base end sections.
[0036] Further, in the embodiment, a distance between the leading
end sections 10b and 11b of each of the vibrating arm sections 10
and 11, and the central axis O is wider than that between the base
end sections 10a and 11a of each of the vibrating arm sections 10
and 11, and the central axis O. That is, when vibrating in the
vibrating arm sections 10 and 11 or when receiving impact from
outside, sufficient clearance is ensured so as not to contact the
leading end sections 10b and 11b of the vibrating arm sections 10
and 11 and a leading end section 12b of the base section 12.
[0037] The clearance is ensured by extending the vibrating arm
sections 10 and 11 from the base end sections 10a and 11a in a
direction away from the base section 12. That is, the embodiment is
characterized in that the vibrating arm sections 10 and 11 have
bending points P, and the vibrating arm sections 10 and 11 extend
in the direction away from the base section 12 from the base end
sections 10a and 11a of the vibrating arm sections 10 and 11 to the
bending points P, and the vibrating arm sections 10 and 11 extend
along the base section 12 from the bending points P to the leading
end sections 10b and 11b of the vibrating arm sections 10 and 11.
Moreover, there are the bending points P in the embodiment but the
invention of this application is not limited to the embodiment and
the invention may have a "curving" shape. In this case, a starting
point of the curving is referred to as "the bending point".
[0038] Further, the pair of vibrating arm sections 10 and 11 are
formed so that a crossing angle .theta. of directions D10 and D11
facing from each of the leading end sections 10b and 11b to the
base end sections 10a and 11a, and directions D13 and D14 in which
each of the connecting sections 13 and 14 extends from the base end
section 12a of the base section 12 is greater than 90.degree., in
connecting sections .alpha. and .beta. of the pair of connecting
sections 13 and 14.
[0039] Moreover, if the crossing angle .theta. is greater, the
clearance between the base section 12 and the leading end sections
10b and 11b of the vibrating arm sections 10 and 11 can be great.
However, since there is a concern that the leading end sections 10b
and 11b of the vibrating arm sections 10 and 11 come into contact
with an inner wall of the package, the crossing angle .theta. may
also be determined in consideration of the clearance with the inner
wall of the package. Further, if the crossing angle .theta. is too
great, since there is a possibility that the bending vibration of
the vibrating arm sections 10 and 11 are influenced (for example,
the vibration is not conducted at a stable frequency, strength of
the vibrating arm section is lowered), the crossing angle .theta.
may also be determined in consideration of the influence on the
vibration.
[0040] Moreover, for example, a distance Lb between a leading end
section 12b of the base section 12 and each of the vibrating arm
sections 10 and 11 with respect to a dimension La (for example, 60
.mu.m or the like) of each of the vibrating arm sections 10 and 11
in the width direction is set to be a value (for example, 40 km to
50 .mu.m) depending on the dimension La of each of the vibrating
arm sections 10 and 11 in the width direction.
[0041] The pair of vibrating arm sections 10 and 11 include
excitation electrodes formed of a first excitation electrode 15 and
a second excitation electrode 16, which vibrate the pair of
vibrating arm sections 10 and 11, on a surface of a piezoelectric
body (the piezoelectric plate 24) made of a piezoelectric
material.
[0042] The base section 12 includes a pair of mount electrodes (not
illustrated) by which the first excitation electrode 15 and the
second excitation electrode 16 are electrically connected to
leading-out electrodes 36 and 37, on the surface of the
piezoelectric body (the piezoelectric plate 24) made of the
piezoelectric material.
[0043] The piezoelectric plate 24 includes groove sections 18,
which are formed along a longitudinal direction (an extending
direction) of the vibrating arm sections 10 and 11, respectively,
on both main surfaces of the pair of vibrating arm sections 10 and
11. For example, the groove sections 18 are formed from the side of
the base end of the vibrating arm sections 10 and 11 to
approximately the vicinity of the center thereof. Moreover, here, a
form in which the groove sections 18 are provided in the vibrating
arm sections 10 and 11 is described, but the invention may also be
applicable to a piezoelectric vibrating piece in which the groove
sections 18 are not provided in the vibrating arm sections 10 and
11. Further, the groove section 18 is provided on the side of the
base section 12 from the bending point P but the piezoelectric
vibrating piece 4 of the invention is not limited to the embodiment
and may extend to the side of the leading ends of the vibrating arm
sections 10 and 11 from the bending point P. Further, the groove
section is not formed in the vicinity of the bending point P and
the groove section 18 may be provided on the side of the base
section 12 from the bending point P and/or on the side of the
leading end thereof.
[0044] The excitation electrodes formed of the first excitation
electrode 15 and the second excitation electrode 16 are patterned
on an outer surface of the pair of vibrating arm sections 10 and 11
in a state where the excitation electrodes are electrically
insulated to each other, and vibrate the pair of vibrating arm
sections 10 and 11 at a predetermined frequency in a direction
approaching or separating from each other.
[0045] More particularly, for example, the first excitation
electrode 15 is mainly provided on the groove section 18 of the
first vibrating arm section 10 and both side surfaces of the second
vibrating arm section 11.
[0046] Further, the second excitation electrode 16 is mainly
provided on both side surfaces of the first vibrating arm section
10 and on the groove section 18 of the second vibrating arm section
11.
[0047] The first excitation electrode 15 and the second excitation
electrode 16 are electrically connected to the mount electrodes
(not illustrated) through extraction electrodes (not illustrated)
on both main surfaces of the base section 12, respectively.
[0048] Therefore, a voltage is applied to the piezoelectric
vibrating piece 4 through the mount electrodes (not
illustrated).
[0049] The pair of vibrating arm sections 10 and 11 include a
weight metal film (not illustrated) coated on an outer surface for
adjusting the frequency, so that vibration states of the pair of
vibrating arm sections 10 and 11 themselves are adjusted to be
vibrated within a range of a predetermined frequency.
[0050] The weight metal film (not illustrated) includes, for
example, a rough adjustment film (not illustrated) for roughly
adjusting the frequency and a fine adjustment film (not
illustrated) for finely adjusting the frequency.
[0051] The frequency adjustment is performed by weight adjustment
of the rough adjustment film and the fine adjustment film, and the
frequency of the pair of vibrating arm sections 10 and 11 is
adjusted so as to fit within a range of a predetermined target
frequency.
[0052] For example, as illustrated in FIG. 3, the piezoelectric
vibrating piece 4 is bump bonded on the leading-out electrodes 36
and 37 which are provided on a surface (a surface facing the lid
substrate 3) of the base substrate 2 by a bump B such as gold.
Moreover, if a ceramic package is used, it is also possible to
mount the piezoelectric vibrating piece 4 on the base substrate of
the ceramic by a conductive adhesive.
[0053] More particularly, the first excitation electrode 15 of the
piezoelectric vibrating piece 4 is bump bonded on the second
leading-out electrode 37 through a first mount electrode (not
illustrated) and the bump B and the second excitation electrode 16
is bump bonded on the first leading-out electrode 36 through a
second mount electrode (not illustrated) and the bump B.
[0054] Therefore, the piezoelectric vibrating piece 4 is supported
in a state of being floated from the surface (the surface facing
the lid substrate 3) of the base substrate 2 and each of the mount
electrodes (not illustrated) is electrically connected to each of
the leading-out electrodes 36 and 37. Moreover, in the base
substrate 2, a concave section may be provided in a region facing
the leading end section of the piezoelectric vibrating piece 4. It
is possible to reduce the possibility of the leading end section of
the piezoelectric vibrating piece 4 from coming into contact with
the base substrate 2 which causes cracks, defects or the like occur
in the leading end section due to external impact by providing the
concave section.
[0055] The lid substrate 3 is formed in a plate shape by a
transparent insulating substrate made of a glass material, for
example, soda-lime glass. Then, a rectangular concave section 3a
capable of accommodating the piezoelectric vibrating piece 4 is
included on the side of the bonding surface to which the base
substrate 2 is bonded. Moreover, in a case of the ceramic package,
a lid made of metal is bonded by brazing material or the like.
[0056] The concave section 3a forms the cavity C accommodating the
piezoelectric vibrating piece 4 by a surface (a surface facing the
lid substrate 3) of the base substrate 2 when overlapping both
substrates 2 and 3 to each other.
[0057] The lid substrate 3 includes the bonding material 35 which
is provided on the entire surface thereof facing the base substrate
2. For example, the bonding material 35 is provided over the
bonding surface with the base substrate 2 and the entire inner
surface of the concave section 3a. In a state where the concave
section 3a faces toward the side of the base substrate 2, the lid
substrate 3 is anode bonded to the base substrate 2 through the
bonding material 35, and hermetically seals the cavity C.
[0058] Similar to the lid substrate 3, the base substrate 2 is
formed in a plate shape having a size capable of overlapping the
lid substrate 3 by a transparent insulating substrate made of a
glass material, for example, soda-lime glass or by a ceramic
material. The base substrate 2 includes a pair of through holes 30
and 31 that pass through in a thickness direction and are open in
the cavity C.
[0059] More particularly, for example, the first through hole 30 of
the through holes 30 and 31 of the embodiment is formed in a
position facing the base end section 12a of the base section 12 of
the piezoelectric vibrating piece 4 that is mounted. Further, the
second through hole 31 is formed in a position facing between the
leading end sections 10b and 11b of the vibrating arm sections 10
and 11. Further, the through holes 30 and 31 are formed in a
tapered shape in a cross-section thereof in which diameters thereof
are gradually reduced from a first surface to a second surface (a
surface facing the lid substrate 3) of the base substrate 2.
[0060] Moreover, in the embodiment, each of the through holes 30
and 31 is formed in the tapered shape in the cross-section thereof
but the invention is not limited to the embodiment, and, for
example, each of the through holes 30 and 31 may be a through hole
which passes through the base substrate 2 in the thickness
direction with a uniform diameter, and may pass through the base
substrate 2.
[0061] The pair of through holes 30 and 31 include the pair of
penetration electrodes 32 and 33 which are formed so as to fill
each of the through holes 30 and 31. The penetration electrodes 32
and 33 are formed of cylindrical bodies 6 and core material
sections 7 that are integrally fixed to the through holes 30 and 31
by burning. The penetration electrodes 32 and 33 maintain
airtightness in the cavity C by blocking the through holes 30 and
31, and electrically connect the external electrodes 38 and 39, and
the leading-out electrodes 36 and 37.
[0062] More particularly, for example, the first penetration
electrode 32 is disposed by facing the leading-out electrode 36
between the external electrode 38 and the base section 12, and the
second penetration electrode 33 is disposed by facing the
leading-out electrode 37 between the external electrode 39 and a
portion between the leading end sections 10b and 11b of the
vibrating arm sections 10 and 11.
[0063] The cylindrical body 6 is formed by baking paste-formed
glass frit. Moreover, in a case of a ceramic package, the
penetration electrode is formed by a via electrode.
[0064] More particularly, for example, the cylindrical body 6 is
formed in a cylindrical shape having flat opposite ends and
substantially the same thickness as the base substrate 2. Then, the
cylindrical body 6 fixes the core material section 7 that is
inserted in a center hole passing through the cylindrical body 6 in
the thickness direction.
[0065] Further, in the embodiment, an external shape of the
cylindrical body 6 is formed so as to be conical (tapered
cross-section) according to the shape of the through holes 30 and
31. Then, the cylindrical body 6 is burned in a state of being
filled in the through holes 30 and 31, and is firmly fixed to the
through holes 30 and 31.
[0066] The core material section 7 is a conductive core material
formed in a cylindrical shape by a metal material and, similar to
the cylindrical body 6, has flat opposite ends and substantially
the same thickness as the base substrate 2.
[0067] The core material section 7 is positioned in a center hole
6c of the cylindrical body 6 and is firmly fixed to the cylindrical
body 6 by burning of the cylindrical body 6. Then, electronic
conductivity is ensured in the penetration electrodes 32 and 33 by
the core material section 7 having conductivity.
[0068] The base substrate 2 includes the pair of leading-out
electrodes 36 and 37 that are patterned by a conductive material
(for example, aluminum) on a surface on the side of the bonding
surface in which the lid substrate 3 is bonded. The pair of
leading-out electrodes 36 and 37 electrically connect the first
penetration electrode 32 of the pair of penetration electrodes 32
and 33, and the second mount electrode (not illustrated) of the
piezoelectric vibrating piece 4, and electrically connect the
second penetration electrode 33 and the first mount electrode (not
illustrated) of the piezoelectric vibrating piece 4.
[0069] More particularly, for example, the first leading-out
electrode 36 is provided to extend toward a supporting section 36a
that is disposed in the leading end section 12b of the base section
12 from the first penetration electrode 32 that is disposed in the
base end section 12a of the base section 12 along the axial
direction of the central axis O.
[0070] The first leading-out electrode 36 supports the leading end
section 12b of the base section 12 by bump bonding by the bump B of
the supporting section 36a in a state of being floated from the
surface (the surface facing the lid substrate 3) of the base
substrate 2, and is electrically connected to the second mount
electrode (not illustrated) of the piezoelectric vibrating piece
4.
[0071] The second leading-out electrode 37 is provided to extend
toward a supporting section 37a that is disposed in the leading end
section 12b of the base section 12 from the second penetration
electrode 33 that is disposed in the position between the leading
end sections 10b and 11b of the pair of vibrating arm sections 10
and 11 along the axial direction of the central axis O.
[0072] The second leading-out electrode 37 supports the leading end
section 12b of the base section 12 by bump bonding by the bump B of
the supporting section 37a in a state of being floated from the
surface (the surface facing the lid substrate 3) of the base
substrate 2, and is electrically connected to the first mount
electrode (not illustrated) of the piezoelectric vibrating piece
4.
[0073] Therefore, the second mount electrode (not illustrated) of
the piezoelectric vibrating piece 4 is electrically connected to
the first penetration electrode 32 through the first leading-out
electrode 36. The first mount electrode (not illustrated) is
electrically connected to the second penetration electrode 33
through the second leading-out electrode 37.
[0074] The base substrate 2 includes the external electrodes 38 and
39 electrically connected to the pair of penetration electrodes 32
and 33, respectively, on the first surface.
[0075] The first external electrode 38 is electrically connected to
the second excitation electrode 16 of the piezoelectric vibrating
piece 4 through the first penetration electrode 32 and the first
leading-out electrode 36.
[0076] Further, the second external electrode 39 is electrically
connected to the first excitation electrode 15 of the piezoelectric
vibrating piece 4 through the second penetration electrode 33 and
the second leading-out electrode 37.
[0077] The piezoelectric vibrator 1 is operated by applying a
predetermined driving voltage with respect to the external
electrodes 38 and 39 formed in the base substrate 2, and vibrates
the pair of vibrating arm sections 10 and 11 at a predetermined
frequency in a direction approaching and separating from each other
by flowing a current in the excitation electrodes formed of the
first excitation electrode 15 and the second excitation electrode
16 of the piezoelectric vibrating piece 4.
[0078] The vibration of the pair of vibrating arm sections 10 and
11 is used as a time source, a timing source of a control signal, a
reference signal source or the like.
[0079] As described above, according to the piezoelectric vibrating
piece 4 of the embodiment, the vibrating arm sections 10 and 11
have the bending points P. The vibrating arm sections 10 and 11
extend in the direction away from the base section 12 from the base
end sections 10a and 11a of the vibrating arm sections 10 and 11 to
the bending points P, and the vibrating arm sections 10 and 11
extend along the base section 12 from the bending points P to the
leading end sections 10b and 11b of the vibrating arm sections 10
and 11. Therefore, it is possible to widen the clearance between
the leading end sections 10b and 11b of the vibrating arm sections
10 and 11, and the base section 12 without increasing the length of
the connecting sections 13 and 14 (the length of the piezoelectric
vibrating piece 4 in the width direction), in other words, without
increasing the distance of a fork section between the piezoelectric
vibrating piece 4 and the base section 12.
[0080] As described above, if the length of the connecting sections
13 and 14 are increased, it is known that the connecting sections
13 and 14 themselves are liable to vibrate and the equivalent
serial resistance value R2 of the secondary high-harmonic wave mode
is reliable to decrease, but according to the embodiment, since
there is no need to increase the length of the connecting sections
13 and 14, it is possible to avoid the contact between the leading
end sections 10b and 11b of the vibrating arm sections 10 and 11,
and the base section 12 while vibrating the piezoelectric vibrating
piece 4 in the fundamental wave mode without decreasing R2.
[0081] Further, since the contact between the leading end sections
10b and 11b of the vibrating arm sections 10 and 11, and the base
section 12 can be avoided, it is possible to increase the
longitudinal dimension of the base section 12, that is, to mount
the piezoelectric vibrating piece 4 in a wider range. Therefore, it
is possible to improve mounting strength of the piezoelectric
vibrating piece 4.
[0082] Further, it is possible to sufficiently attenuate the
vibration, which is generated in the vibrating arm sections 10 and
11, in the base section 12 by increasing the longitudinal dimension
of the base section 12. Therefore, it is possible to reduce
so-called vibration leakage, that is, vibration leaked on the side
of the package which is generated in the vibrating arm sections 10
and 11.
[0083] Further, according to simulations carried out by the
inventors, when a length from the base end sections 10a and 11a to
the leading end sections 10b and 11b of the vibrating arm sections
10 and 11 is L1, and a length from the base end sections 10a and
11a of the vibrating arm sections 10 and 11 to the bending points P
is L2, it is recognized that the vibrating arm sections 10 and 11
can further reliably vibrate in the fundamental wave mode if
L2/L1>0.17 is satisfied.
[0084] That is, if L2/L1 is small, in other words, if the bending
points P are near the base end sections 10a and 11a of the
vibrating arm sections 10 and 11, it is necessary to increase the
crossing angle .theta. to sufficiently ensure the clearance in the
leading end sections 10b and 11b of the vibrating arm sections 10
and 11. However, if the crossing angle .theta. is increased, as
described above, the problem of coming into contact with the
package or the vibratory problem of being difficult to bending
vibrate in the fundamental wave mode occurs. Thus, the inventors
found that the effects described above are further reliably
obtained if L2/L1>0.17, from the results of the simulations
carried out by the inventors to avoid the problems.
Oscillator
[0085] Next, an embodiment of an oscillator according to the
invention is described.
[0086] As illustrated in FIG. 6, an oscillator 100 according to the
embodiment is configured as an oscillator in which the
piezoelectric vibrator 1 is electrically connected to an integrated
circuit 101.
[0087] The oscillator 100 includes the integrated circuit 101 for
the oscillator described above, an electronic part 102 such as a
capacitor, and the piezoelectric vibrating piece 4 of the
piezoelectric vibrator 1 disposed in the vicinity of the integrated
circuit 101 on the substrate 103.
[0088] The electronic part 102, the integrated circuit 101 and the
piezoelectric vibrator 1 are electrically connected to each other
by a wiring pattern (not illustrated).
[0089] Moreover, each of the configuration parts is molded by a
resin (not illustrated).
[0090] In the oscillator 100 configured as described above, if a
voltage is applied to the piezoelectric vibrator 1, the
piezoelectric vibrating piece 4 vibrates in the piezoelectric
vibrator 1.
[0091] The vibration is converted into an electric signal by
piezoelectric characteristics of the piezoelectric vibrating piece
4 and is input into the integrated circuit 101 as an electric
signal. After various types of processes are performed by the
integrated circuit 101, the input electric signal is output as a
frequency signal. Therefore, the piezoelectric vibrator 1 functions
as the oscillator.
[0092] In addition, it is possible to add functions for controlling
an operation date or time of the apparatus or an external apparatus
or for providing time, calendar or the like in addition to a
single-function oscillator for a timepiece or the like to the
configuration of the integrated circuit 101, for example, by
selectively setting a real time clock (RTC) module or the like upon
request.
[0093] As described above, according to the oscillator 100 of the
embodiment, it is possible to provide the oscillator 100 being of a
high-quality which has superior characteristics and reliability by
including the piezoelectric vibrator 1 described above.
[0094] Further, in addition thereto, it is possible to obtain the
frequency signal with a high accuracy which is stable in a long
period.
Electronic Apparatus
[0095] Next, an embodiment of an electronic apparatus according to
the invention is described.
[0096] Moreover, as an example of the electronic apparatus, a
portable information apparatus 110 having the piezoelectric
vibrator 1 described above is described.
[0097] The portable information apparatus 110 of the embodiment is
represented, for example, by a cellular phone, and develops and
improves a wristwatch of the related art. An outer appearance
thereof is similar to the wristwatch and a liquid crystal display
is arranged in a portion corresponding to a dial, and a current
time or the like can be displayed on a screen.
[0098] In addition, in a case of being used as a communication
apparatus, it is possible to perform the communication similar to
the cellular phone of the related art by removing the wristwatch
from the wrist and by using a speaker and a microphone which are
incorporated in the inner portion of a band. Furthermore, the
portable information apparatus can be significantly downsized and
made lightweight compared to the cellular phone of the related
art.
Portable Information Apparatus
[0099] Next, a configuration of the portable information apparatus
110 of the embodiment is described.
[0100] As illustrated in FIG. 7, the portable information apparatus
110 includes the piezoelectric vibrator 1 and a power supply
section 111 for supplying electric power.
[0101] For example, the power supply section 111 is formed of a
lithium secondary battery.
[0102] A controller 112 that performs various types of control, a
timer section 113 that counts the time or the like, a communication
section 114 that performs the communication with the outside, a
display section 115 that displays various types of information, and
a voltage detecting section 116 that detects the voltage of each of
function sections are connected in parallel to the power supply
section 111.
[0103] Then, power can be supplied from the power supply section
111 to each of the function sections.
[0104] The controller 112 performs operational control of the
entirety of the system such as transmitting and receiving of sound
data, measuring or displaying of a current time or the like by
controlling each of the function sections.
[0105] In addition, the controller 112 includes a ROM in which a
program is written in advance, a CPU that reads and executes the
program written on the ROM, a RAM that is used as a work area of
the CPU or the like.
[0106] The timer section 113 includes an integrated circuit
incorporating an oscillator circuit, a register circuit, a counter
circuit, an interface circuit or the like, and the piezoelectric
vibrator 1.
[0107] If voltage is applied to the piezoelectric vibrator 1, the
piezoelectric vibrating piece 4 vibrates, the vibration is
converted into an electric signal by the piezoelectric
characteristics having the crystal and is input into the oscillator
circuit as the electric signal. The output of the oscillator
circuit is binarized and is counted by the register circuit and the
counter circuit.
[0108] Then, the signal is transmitted to and received from the
controller 112 through the interface circuit and the current time,
the current date, the calendar information or the like is displayed
on the display section 115.
[0109] The communication section 114 has the same function as the
cellular phone of the related art and includes a radio section 117,
a voice processing section 118, a switching section 119, an
amplifier 120, a voice input and output section 121, a phone number
input section 122, a ring sound generator 123, and a call control
memory section 124.
[0110] The radio section 117 transmits and receives various data
such as voice data to/from a base station through an antenna
125.
[0111] The voice processing section 118 codes and decodes the voice
signal input from the radio section 117 or the amplifier 120.
[0112] The amplifier 120 amplifies the signal input from the voice
processing section 118 or the voice input and output section 121 to
a predetermined level.
[0113] The voice input and output section 121 is configured of a
speaker, a microphone or the like, and amplifies the ring sound or
reception voice, or collects voice.
[0114] In addition, the ring sound generator 123 generates the ring
sound in response to a call from the base station. The switching
section 119 switches the amplifier 120 connected to the voice
processing section 118 into the ring sound generator 123 only when
a call is received. Therefore, the ring sound generated in the ring
sound generator 123 is output to the voice input and output section
121 through the amplifier 120.
[0115] Moreover, the call control memory section 124 stores a
program relating to incoming and outgoing call control of the
communication. In addition, the phone number input section 122
includes, for example, number keys from 0 to 9 along with other
keys, and the phone number of a call destination is input by
pressing the number keys.
[0116] If the voltage applied to each of the function sections such
as the controller 112 by the power supply section 111 is below a
predetermined value, the voltage detecting section 116 detects the
voltage drop and notifies the controller 112. At this time, the
predetermined voltage value is a value that is set in advance as a
minimum voltage required to stably operate the communication
section 114 and, for example, is approximately 3 V.
[0117] The controller 112 which receives the voltage drop
notification from the voltage detecting section 116 prohibits
operations of the radio section 117, the voice processing section
118, the switching section 119 and the ring sound generator 123.
Particularly, stopping of the operation of the radio section 117 in
which power consumption is great is essential. Furthermore, the
fact that the communication section 114 cannot be used due to a
deficiency of the battery power is displayed on the display section
115.
[0118] That is, the operation of the communication section 114 is
prohibited by the voltage detecting section 116 and the controller
112, and the fact can be displayed on the display section 115. The
display may be a text message and may be a x (cross) mark on a
phone icon displayed in an upper portion of a display surface of
the display section 115 as a more intuitive display.
[0119] Moreover, it is possible to further reliably stop the
function of the communication section 114 by including a power
shutdown section 126 capable of selectively cutting the power
source of a portion according to the function of the communication
section 114.
[0120] As described above, according to the portable information
apparatus 110 of the embodiment, it is possible to provide the
portable information apparatus 110 being of a high quality which
has superior characteristics and reliability by including the
piezoelectric vibrator 1 described above. Further, in addition
thereto, it is possible to display the time information with a high
accuracy which is stable in a long period.
Radio Controlled Timepiece
[0121] Next, an embodiment of a radio controlled timepiece
according to the invention is described with reference to FIG.
8.
[0122] As illustrated in FIG. 8, the radio controlled timepiece 130
of the embodiment includes the piezoelectric vibrator 1
electrically connected to a filter section 131 and is a timepiece
having functions for displaying the correct time by automatic
correction by receiving a standard radio wave including timepiece
information.
[0123] There are transmitting stations which transmit the standard
radio waves in Fukushima (40 kHz) and Saga (60 kHz) in Japan, and
the transmitting stations transmit the standard radio waves,
respectively. Since a long wave such as 40 kHz or 60 kHz has both a
property of propagating through the surface of the earth and a
property of propagating through an ionized layer and the surface of
the earth while being reflected, a propagation range is wide and
can cover the entirety of Japan with the two transmitting stations
described above.
[0124] Hereinafter, a functional configuration of the radio
controlled timepiece 130 is described in detail.
[0125] An antenna 132 receives the standard radio wave of the long
wave such as 40 kHz or 60 kHz. The standard radio wave of the long
wave is obtained by applying AM modulation on a carrier wave of 40
kHz or 60 kHz to the time information referred to as a time code.
The standard radio wave of the long wave which is received is
amplified by an amplifier 133, and is filtered and tuned by the
filter section 131 having a plurality of piezoelectric vibrators
1.
[0126] The piezoelectric vibrators 1 of the embodiment include
crystal vibrator sections 138 and 139 having the resonance
frequency of 40 kHz and 60 kHz which is the same as the carrier
frequency described above, respectively.
[0127] Further, a signal of a predetermined frequency which is
filtered is detected and demodulated by a detection and
rectification circuit 134. Then, the time code is extracted through
a waveform shaping circuit 135 and is counted in a CPU 136.
[0128] The CPU 136 reads information such as the current year, the
number of days, the day of the week, time or the like. The
information that is read is reflected in an RTC 137 and correct
time information is displayed.
[0129] Since the carrier wave is 40 kHz or 60 kHz, as the crystal
vibrator sections 138 and 139, the vibrator having the tuning fork
type structure described above is suitable.
[0130] Moreover, the above description is illustrated in the
example in Japan but the frequency of the standard radio wave of
the long wave is different in foreign countries. For example, the
standard radio wave of 77.5 KHz is used in Germany. Therefore, if
the radio controlled timepiece 130 capable of corresponding to
foreign countries is incorporated in the portable apparatus, it is
necessary to provide the piezoelectric vibrator 1 having a
frequency different from that in Japan.
[0131] As described above, according to the radio controlled
timepiece 130 of the embodiment, it is possible to provide the
radio controlled timepiece 130 being of a high quality which has
superior characteristics and reliability by including the
piezoelectric vibrator 1 described above. Further, in addition
thereto, it is possible to count the time with a high accuracy
which is stable in a long period.
[0132] Further, a technical range of the invention is not limited
to the embodiments and various modifications can be applied without
departing from the scope of the invention.
[0133] For example, in the above embodiments, the piezoelectric
vibrating piece 4 of the invention is employed in the piezoelectric
vibrator 1 of the surface mount type but the invention is not
limited to the embodiment. For example, the piezoelectric vibrator
of the surface mount type may be formed by further fixing a
piezoelectric vibrator of a ceramic package type or a piezoelectric
vibrator of a cylinder package type of the related art, with a mold
resin section.
* * * * *